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Need help with PhysioEX: Cell Transport Mechanisms and Permeability... Exercise 1 :thu:

Activity 1 through 5...

Activity 1: Simulating Dialysis (Simple Diffusion) (pp. 2–4)
Activity 2: Simulating Facilitated Diffusion (pp. 4–5)
Activity 3: Simulating Osmotic Pressure (pp. 6–7)
Activity 4: Simulating Filtration (pp. 7–9)
Activity 5: Simulating Active Transport (pp. 10–11)

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If you increased (or doubled) the concentration of albumin, osmotic pressure will increase (or double). Glucose is freely diffusible using the 200 MWCO membrane and therefore has no effect on osmotic pressure. The 100 MWCO membrane does not allow glucose to pass and therefore glucose will generate an osmotic influence. Because albumin concentration in the left beaker is 9.00 mM and glucose concentration in the right beaker is 10.00 mM (1.00 mM higher than the left), the small gradient dictates that an osmotic pressure increase will appear in the right beaker.

Activity 4: Simulating Filtration (pp. 7–9)

9. Smaller MWCO numbers translate to smaller pore sizes, which correlate with lower filtration rate. Powdered charcoal did not appear in the filtrate using any membrane. Increasing the force driving filtration increases filtration rate. Increasing the pressure gradient effectively increases the filtration rate. By examining the filtration results, we can predict that the molecular weight of glucose must be greater than NaCl but less than powdered charcoal.

Activity 5: Simulating Active Transport (pp. 10–11)

7. Solute transport stops before the completion of transport because of a lack of ATP. Sodium and potassium transport will not occur if ATP is not available.

8. Yes, transport has changed because more ATP is available. This fact supports the earlier supposition that ATP is required for active transport. The rate of active transport will decrease if fewer solute pumps are available, but will still go to completion given enough ATP and time. You can show that this is an active process by making the sodium concentration in the right beaker greater than the sodium concentration in the left beaker. Transport will occur against the concentration gradient in active transport but not in diffusion.

9. Sodium transport is not affected by putting NaCl into the right beaker. Increasing the number of pump proteins will increase solute transport. Glucose presence does not affect active transport.

Thanks Duddy!